1. Field of the Invention
The present invention relates to a body frame of a motorcycle having a reinforcing member which reinforces a connecting portion of a head pipe and other frame members.
2. Description of the Related Art
A body frame of a motorcycle mainly has a head pipe for pivotally supporting a steering shaft having an upper portion on which a steering wheel is mounted, a main frame extended rearward from the head pipe, and a down frame extended downward from the head pipe. Some body frames also have a lower frame extended substantially rearward from a lower end of the down frame, and a swing arm bracket connecting a rear end of the lower frame and a rear end of the main frame (for instance, see Japanese Patent Laid-open Publication No. 2009-234579).
The body frame in Japanese Patent Laid-open Publication No. 2009-234579 has, as separated members, a gusset reinforcing a joined portion of the main frame to the head pipe and a support bar supporting the main frame, which are joined by welding.
In this way, high stress based on a road surface input and an acceleration and deceleration input is likely to occur around the head pipe of the body frame. High strength is thus required around the head pipe. Further, stress is likely to concentrate onto a welded portion which joins these members. Consequently, more careful quality control is required for the welded portion around the head pipe, resulting in lowered productivity.